Free lobster meal costs Guy votes: Poll

He may not have paid for his seafood platter, but Victorian opposition leader Matthew Guy's lobster with a mobster scandal has cost him votes, a new poll shows.

Labor would romp home if an election were held at the weekend, with about a third of people polled in four marginal seats less likely to vote Liberal because of the controversy, according to the ReachTel poll commissioned by Fairfax media.

In two-party preferred figures, Labor would build on the 2014 result, getting 56 per cent of the vote in Bentleigh, 52 per cent in Frankston, 55 per cent in Mordialloc and 51 per cent in Carrum.

Mr Guy admitted last week to sharing a dinner with accused mafia boss Tony Madafferi at the Lobster Cave in April.

He says he was invited to the dinner by long-term Liberal member and Mr Madafferi's cousin, Frank Lamattina, to discuss fruit and vegetable markets and not donations.

He also said he did not know Mr Madafferi would be at the dinner until he arrived.

However, leaked phone calls made by Liberal figure Barrie MacMillan suggest the meeting was designed to direct donations to the cash-strapped party.

Mr Guy and the coalition have been running a tough on crime agenda against the Andrews government, but that campaign came under attack when parliament resumed last week with robust pot shots from the government.

And deputy premier James Merlino was issued with legal threats from Mr Madafferi for comments made outside of parliament.

Mr Madafferi is widely accused of being a high-level organised crime figure, but he has never been charged or convicted and strenuously denies any allegations.